What makes for a harsh environment? For a person, a harsh or inhospitable environment could be considered a set of conditions that can cause bodily harm over a period of time. The concept is much the same for electronics; for example, an electrical circuit can be easily damaged or destroyed if introduced to water or high humidity levels. Other potentially damaging conditions include extreme temperatures and temperature cycles, ingress of particulates, electrostatic discharge (ESD), electromagnetic interference (EMI), vibrations, and physical impact.
Many applications need electronics that are designed to operate in harsh environments. The downhole oil and gas industry is one such example, requiring high-reliability parts with temperature ratings which often surpass military specifications. Standards, such as NEMA ratings and the IP code (IEC 60529), exist to quantify the degree to which a product can withstand various harsh conditions.
Engineers must take into account a harsh environment prior to the design stage of development. The specific environmental conditions in which the product will be used will affect the product specifications, and must be determined beforehand.